Portable power chain saw



Nov. 5, 1968 A. RAUH 3,409,056

PORTABLE POWER CHAIN SAW Filed Sept. 15, 1965 2 Sheets-Sheet l Nov. 5,1968 A. RAUH 3,409,056

PORTABLE POWER CHAIN SAW Filed Sept. 13, 1965 2 Sheets-Sheet 2 2i Fig.4

United States Patent 3,409,056 PORTABLE POWER CHAIN SAW Albrecht Rauh,Im Weinberg, Kleinheppach, Germany, as-

signor to Andreas Stihl Maschinenfabrik, Waiblingen, Germany Filed Sept.13, 1965, Ser. No. 486,775 9 Claims. (Cl. 143-32) ABSTRACT OF THEDISCLOSURE Portable chain saw having a drive engine and a support handleunit having a transverse and a longitudinal handle rigidlyinterconnected with vibration damping bushings at the ends of thetransverse handle and the rear end of the longitudinal handle whichconnect the handle unit to the saw structure and eliminate vibrations.

This invention relates to a portable power chain saw, which comprisestwo handles, which are mounted with vibration-damping mountings ofresilient material on the front and rear portions of the motor unit,respectively.

It has been endeavored for a long time effectively to damp the vibrationset up in power chain saws by highspeed drive motors because thiscontinuous vibration has a highly adverse effect on the operation of thepower chain saw and in many cases inflicts health damage on personswhich are subjected to this stress for a prolonged time. It is known touse so-called sandwich-type vibration-damping mountings or othervibration-damping materials for mounting the handles of power saws onthe machine frame. Such handles comprise usually a handle for the lefthand of the operator and one for the right hand of the operator, and aresecured to the front and rear portions of the motor unit, respectively.With this known mounting arrangement for the handles, an effectivevibration damping can only be accomplished if the rubberlike resilientmounting between the handle and the motor unit is sulficiently soft sothat the vibration generated by the motor is sufiiciently damped and isnot transmitted to the handles.

On the other hand, if the rubberlike resilient mountings are soft as isrequired for an effective damping of vibration, a reliable control ofthe bodily movement of the power saw is no longer ensured although suchcontrol is essential. With vibration-damping mountings for handles ofthe type described hereinbefore, it has been found that the cuttingforces, which act on a relatively long lever arm constituted by theguide bar for the .saw chain, laterally displace the motor unit relativeto the handles owing to the soft mounting so that there is a lack ofcontrol of the bodily movement of the chain of the power saw duringoperation. For this reason, the known mountings described hereinbeforefor the handles of portable power saws have become abandoned.

It is an object of the invention to provide for the bandies of powersaws an arrangement which effects a strong damping of the undesiredvibration and ensures that the connection between the handles on the onehand, and the motor unit and guide bar, on the other hand, has therigidity which is required for a reliable operation of the power saw.

In a power saw which comprises two handles that are connected byvibration-damping mountings of resilient material to the front and rearportions of the machine, these conflicting requirements are fulfilledaccording to the invention in that a rigid connection is providedbetween the front and rear handles. The rigid connection between thefront handle, for the left hand, and the rear handle, for the right handof the operator, may have any desired design and location. It is merelyessential that the two handles are rigidly interconnected so that thehandles ice together with the rigid connectionform a stable frame, whichis separate from the motor-unitand is connected to it byvibration-damping mountings, preferably at three points. Thus, thehandles which are connectcd'in a rigid carrying frame are resilientlymounted on the motor at three points, which are spaced apart. l

In a preferred embodiment of the invention, two rubberlike resilientmountings are provided at the front end of the power saw, considered inthe feeding direction, these mountings are spaced apart and extendtransversely to the feeding direction, and the. third mounting for therear handle is provided at the rear of the motor.

The two rubberlike resilient mountings at the front end may be connectedto each other by a generally U-shaped handle, which extends transverselyto theguide bar. This U-shaped handle has an intermediate grip portion,.to which a spar connected to the rearhandle-is rigidly secured. Theinvention provides a frame for mounting the motor unit, and the motorunit is supported in this frame in the main direction of movement of thevibration-gencrating motor members, such as the crankshaft, connectingrod, and pistons, by known vibration-damping resilient mountings, suchas rubber mountings, sandwich-type mountings etc., at three points,which are spaced apart as far as possible. The provision of a rigidconnection between the front and rear handles and the fact that thestable carrying frame, formed with the aid of this rigid connection, forthe power saw is mounted preferably at three points ensures asurprisingly damping of the vibration transmitted from the motor to thestrong handles as well as a sufficiently rigid connection between thehandles and the power chain saw.

The invention will now be explained more fully with reference to thedrawings, in which FIG. 1 is a perspective View showing a power chainsaw, in which the guide bar and the saw chain guided by it are shownbroken off at the forward end.

FIG. 2 is a side view of a chain saw having a different configurationfrom that of FIGURE 1 and looking in the direction of the arrow II inFIGURE 3.

.FIG. 3 is a top plan view looking in the direction of the arrow III inFIG. 2. 1

FIG. 4 is a front elevation taken in the direction of arrow IV in FIG.3.

The power chain saw comprises in known manner a drive motor 1 not shownin detail and having a crankshaft, which is indicated only by its axisof rotation 2. The pulling handle for starting the drive motor isindicated at 3. A fuel tank 4 is disposed below the drive motor. Thedrive motor is combined with the fuel tank and accessories in a compactunit, which will be referred to as a motor unit. The guide bar 5 isconnected to the front end of this unit. The saw chain 7 extends aroundthis guide bar and is driven by the motor in the direction of arrow 6.The carrying handle 8 for the left hand of the operator is provided atthe front end of the motor unit. The carrying handle 9 for the righthand of the operator is disposed at the rear end of the motor unit. Arigid connection 10 in the form of a connecting spar is provided betweenthe front and rear handles 8 and 9 and together with the carryinghandles 8 and 9 forms a rigid frame for the motor unit. This frame issecured to the motor unit by three points. In the embodiment shown byway of example, the front handle 8 is secured to. the motor unit at twopoints which are spaced apart transversely to the feeding direction ofthe power saw. The mounting 13 for the rear handle 9 forms the rearmounting. The mountings 11, 12, 13 are sandwich-type, rubberlikeresilient mountings. The rubberlike resilient mountings 11 12, 13 aresuitably arranged so that the lugs 14, 15 or 16 rigidly secured to themotor unit extend at right angles to the crankshaft axis 2. In otherwords, the axes gf these mountings are parallel to the axis of rotation2 of the crankshaft. This orientation does not only ensure a strongdamping but causes the rubberlike resilient mountings to be stressedmainly in' shears and less in compression or tension. It is essentialthat the rigid frame which has been providedfor the motor unit isconnected to the motor unit by vibration damping mountings at threepoints, which are spaced apart. Two of the mountings may be disposed atthe rear or front end of the motor unit and the third mounting must bedisposed at that end which is opposite to the two other mountings. Therigid connectionwhich is provided according to the invention between thefront and rear handles and the mounting of the resulting rigid carryingframe on the motor unit at three points result in a surprisingly strongdamping. At the same time, the motor unit can vibrate freely withouttransmitting its vibration to the handles. In a development of theinvention, the rigid connection or the frame including this rigidconnection may carry parts of the power saw which need not be rigid withthat part of the saw which carries the crankshaft, such as the airfilter, carburetor or particularly the fuel tank, which is connected tothe motor by a flexible tube. The rigid connection between thefront andrear handles of the power saw is shown in FIG. 1 to be disposed over themotor unit but may be disposed as desired, e.g. on the side of the motorblock or below the same.

In the modification of FIGURES 2-4, the same invention principle isillustrated but the configuration of the chain saw is somewhatdifferent. The numerals employed in FIGURES 2-4 are the same as thatused on FIGURE 1 but have been increased by 20.

- It will be understood that this invention is susceptible tomodification in order to adapt it to different usages and conditions;and accordingly, it is desired to comprehend such modifications withinthis invention as may fall within the scope of the appended claims.

' What I claim is:

1. A'portable power chain saw which comprises; a saw chain, a motor unithaving front and rear ends and a crankshaft between said ends operableto drive said chain, a chain supporting and guiding member connected toand extending from the front end of said motor unit, said chain beingguided and supported by said member, a rigid handle unit having aplurality of spaced regions adapted for connection to correspondinglyspaced regions on said motor unit, means connecting each said region ofthe handle unit to a pertaining region of the motor unit and including aresilient vibration damping element interposed between each pertainingpair of said regions, said handle unit comprising a transverse handlehaving two of said regions thereon at the ends thereof and alongitudinal handle fixed at one end to said transverse handle andhaving at the other end another of said regions, the said two of saidregions on the handle unit being disposed on the side of the axis ofsaid crankshaft toward one end of said engine and the said other of saidregions on said handle unit being disposed on the other side of the axisof said crankshaft.

2. A portable power chain saw according to claim 1 in which said tworegions on said handle unit are in the front side of the axis of saidcrankshaft while said other region on said handle unit is on the rearside of the axis of said crankshaft.

3. A portable power chain saw according to claim 1 in which the plane ofsaid supporting and guiding member passes between the said two regionson said handle unit.

4. A portable power chain saw according to claim 2 in which the plane ofsaid supporting and guiding member passes between the said two regionson said handle unit.

r 5. A portable power chain saw according to claim 1 in which said tworegions on the handle unit are located at respectively different heightswith regard to the horizontal when said saw is held with said supportingand guiding member in a vertical plane and extending horizontallyoutwardly from said motor unit.

'6. A portable power chain saw according to claim 1 in which each saidregion on said motor unit and on said handle unit comprises elasticelement engaging surface means, said surface means extendingsubstantially parallel to the plane of said supporting and guidingmember and each said surface means on the motor unit being spaced fromthe pertaining said surface means on the handle unit in a directionperpendicular to said surface means to thereby form pairs of saidsurface means, and each said elastic element being interposed betweenand in engagement with a respective pair of said surface means wherebyloads on said supporting and guiding member in the direction of thelength there-of load said elastic elements in shear whereas loads onsaid supporting and guiding member perpendicular to the plane thereofloads said elastic elements in tension and compression.

'7. A portable power chain saw according to claim 6 in which said motorunit comprises a casing in which said motor is rigidly mounted and saidregions on said motor unit are formed on said casing and comprise atleast in part attachment members fixed to and projecting from saidcasing.

8. A portable power chain saw according to claim 6 in which saidtransverse handle is disposed at the front end of said motor unit andsaid longitudinal handle has its front end fixed to an intermediatepoint of said transverse handle and extends rearwardly therefrom to therear end of said motor unit.

9. A portable power chain saw which comprises; a saw chain, a motor unithaving front and rear ends and a crankshaft between said ends operableto drive said chain, a chain supporting and guiding member connected toand extending from the front end of said motor unit, said chain beingguided and supported by said member, a rigid handle unit having aplurality of spaced regions adapted for connection to correspondinglyspaced regions on said motor unit, means connecting each said region ofthe handle unit to a corresponding region of the motor unit andincluding a resilient vibration damping element interposed between eachcorresponding pair of said regions, said handle unit comprising a handleportion extending from the front end to the rear end of said motor unitand spanning the axis of said crankshaft, the forward end of said handleportion being connected to said motor unit through a pair of saidcorresponding regions on the side of said axis at the front end andthrough another pair of said corresponding regions on the side of saidaxis at the rear, said handle unit being also connected to said motorunit through a third pair of corresponding regions which aretransversely spaced from and on the opposite side of the longitudinalcenter line from at least one of said first two pairs of regions.

References Cited UNITED STATES PATENTS 2,630,784 3/1953 Wallerstein173162 X 3,140,746 7/1964 La Force 173-162 3,152,650 10/1964 Savidge173162 3,224,473 12/1965 Dobbertin 143-32 FOREIGN PATENTS 565,78311/1944 Great Britain.

DONALD R. SCHRAN, Primary Examiner.

